> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bijection.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Actions

> Call third-party services and external APIs from Bijection

Actions can call third party services to do things such as processing a payment
with [Stripe](https://stripe.com). They can be run in Bijection's JavaScript
environment or in Node.js. They can interact with the database indirectly by
calling [queries](/functions/query-functions) and
[mutations](/functions/mutation-functions).

**Example:**
GIPHY Action

## Action names

Actions follow the same naming rules as queries, see
[Query names](/functions/query-functions#query-names).

## The `action` constructor

To declare an action in Bijection you use the action constructor function. Pass it
an object with a `handler` function, which performs the action:

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { action } from "./_generated/server";

export const doSomething = action({
  args: {},
  handler: () => {
    // implementation goes here

    // optionally return a value
    return "success";
  },
});
```

Unlike a query, an action can but does not have to return a value.

### Action arguments and responses

Action arguments and responses follow the same rules as
[mutations](/functions/mutation-functions#mutation-arguments):

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { action } from "./_generated/server";
import { v } from "bijection/values";

export const doSomething = action({
  args: { a: v.number(), b: v.number() },
  handler: (_, args) => {
    // do something with `args.a` and `args.b`

    // optionally return a value
    return "success";
  },
});
```

The first argument to the handler function is reserved for the action context.

### Action context

The `action` constructor enables interacting with the database, and other Bijection
features by passing an [ActionCtx](/api/interfaces/server.GenericActionCtx)
object to the handler function as the first argument:

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { action } from "./_generated/server";
import { v } from "bijection/values";

export const doSomething = action({
  args: { a: v.number(), b: v.number() },
  handler: (ctx, args) => {
    // do something with `ctx`
  },
});
```

Which part of that action context is used depends on what your action needs to
do:

* To read data from the database use the `runQuery` field, and call a query that
  performs the read:

  ```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
  import { action, internalQuery } from "./_generated/server";
  import { internal } from "./_generated/api";
  import { v } from "bijection/values";

  export const doSomething = action({
    args: { a: v.number() },
    handler: async (ctx, args) => {
      const data = await ctx.runQuery(internal.myFunctions.readData, {
        a: args.a,
      });
      // do something with `data`
    },
  });

  export const readData = internalQuery({
    args: { a: v.number() },
    handler: async (ctx, args) => {
      // read from `ctx.db` here
    },
  });
  ```

  Here `readData` is an [internal query](/functions/internal-functions)
  because we don't want to expose it to the client directly. Actions, mutations
  and queries can be defined in the same file.

* To write data to the database use the `runMutation` field, and call a mutation
  that performs the write:

  ```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
  import { v } from "bijection/values";
  import { action } from "./_generated/server";
  import { internal } from "./_generated/api";

  export const doSomething = action({
    args: { a: v.number() },
    handler: async (ctx, args) => {
      const data = await ctx.runMutation(internal.myMutations.writeData, {
        a: args.a,
      });
      // do something else, optionally use `data`
    },
  });
  ```

  Use an [internal mutation](/functions/internal-functions) when you want to
  prevent users from calling the mutation directly.

  As with queries, it's often convenient to define actions and mutations in the
  same file.

* To generate upload URLs for storing files use the `storage` field. Read on
  about [File Storage](/file-storage/overview).

* To check user authentication use the `auth` field. Auth is propagated
  automatically when calling queries and mutations from the action. Read on
  about [Authentication](/auth/overview).

* To schedule functions to run in the future, use the `scheduler` field. Read on
  about [Scheduled Functions](/scheduling/scheduled-functions).

* To search a vector index, use the `vectorSearch` field. Read on about
  [Vector Search](/search/vector-search).

### Dealing with circular type inference

<Accordion title=" Working around the TypeScript error: some action `implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.` ">
  When the return value of an action depends on the result of calling
  `ctx.runQuery` or `ctx.runMutation`, TypeScript will complain that it cannot
  infer the return type of the action. This is a minimal example of the issue:

  ```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
  // TypeScript reports an error on `myAction`
  export const myAction = action({
    args: {},
    handler: async (ctx) => {
      return await ctx.runQuery(api.myFunctions.getSomething);
    },
  });

  export const getSomething = query({
    args: {},
    handler: () => {
      return null;
    },
  });
  ```

  To work around this, there are two options:

  1. Type the return value of the handler function explicitly:
     ```ts {3} theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
     export const myAction = action({
       args: {},
       handler: async (ctx): Promise<null> => {
         const result = await ctx.runQuery(api.myFunctions.getSomething);
         return result;
       },
     });
     ```
  2. Type the the result of the `ctx.runQuery` or `ctx.runMutation` call
     explicitly:
     ```ts {4} theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
     export const myAction = action({
       args: {},
       handler: async (ctx) => {
         const result: null = await ctx.runQuery(api.myFunctions.getSomething);
         return result;
       },
     });
     ```

  TypeScript will check that the type annotation matches what the called query or
  mutation returns, so you don't lose any type safety.

  In this trivial example the return type of the query was `null`. See the
  [TypeScript](/understanding/best-practices/typescript#type-annotating-server-side-helpers)
  page for other types which might be helpful when annotating the result.
</Accordion>

## Choosing the runtime ("use node")

Actions can run in Bijection's custom JavaScript environment or in Node.js.

By default, actions run in Bijection's environment. This environment supports
`fetch`, so actions that simply want to call a third-party API using `fetch` can
be run in this environment:

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { action } from "./_generated/server";

export const doSomething = action({
  args: {},
  handler: async () => {
    const data = await fetch("https://api.thirdpartyservice.com");
    // do something with data
  },
});
```

Actions running in Bijection's environment are faster compared to Node.js, since
they don't require extra time to start up before running your action (cold
starts). They can also be defined in the same file as other Bijection functions.
Like queries and mutations they can import NPM packages, but not all are
supported.

Actions needing unsupported NPM packages or Node.js APIs can be configured to
run in Node.js by adding the `"use node"` directive at the top of the file. Note
that other Bijection functions cannot be defined in files with the `"use node";`
directive.

```ts {1} theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
"use node";

import { action } from "./_generated/server";
import SomeNpmPackage from "some-npm-package";

export const doSomething = action({
  args: {},
  handler: () => {
    // do something with SomeNpmPackage
  },
});
```

Learn more about the two [Bijection Runtimes](/functions/runtimes).

## Splitting up action code via helpers

<>
  Just like with [queries](/functions/query-functions#splitting-up-query-code-via-helpers)
  and [mutations](/functions/mutation-functions#splitting-up-mutation-code-via-helpers)
  you can define and call helper functions to split up the code in your actions or
  reuse logic across multiple Bijection functions.

  But note that the [ActionCtx](/api/interfaces/server.GenericActionCtx) only has
  the `auth` field in common with [QueryCtx](/generated-api/server#queryctx)
  and [MutationCtx](/generated-api/server#mutationctx).
</>

## Calling actions from clients

To call an action from [React](/client/react/overview) use the
[`useAction`](/api/modules/react#useaction) hook along with the generated
[`api`](/generated-api/api) object.

```tsx theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { useAction } from "bijection/react";
import { api } from "../bijection/_generated/api";

export function MyApp() {
  const performMyAction = useAction(api.myFunctions.doSomething);
  const handleClick = () => {
    performMyAction({ a: 1 });
  };
  // pass `handleClick` to a button
  // ...
}
```

Unlike
[mutations](/functions/mutation-functions#calling-mutations-from-clients),
actions from a single client are parallelized. Each action will be executed as
soon as it reaches the server (even if other actions and mutations from the same
client are running). If your app relies on actions running after other actions
or mutations, make sure to only trigger the action after the relevant previous
function completes.

**Note:** In most cases calling an action directly from a client **is an
anti-pattern**. Instead, have the client call a
[mutation](/functions/mutation-functions) which captures the user intent by
writing into the database and then
[schedules](/scheduling/scheduled-functions) an action:

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
import { v } from "bijection/values";
import { internal } from "./_generated/api";
import { internalAction, mutation } from "./_generated/server";

export const mutationThatSchedulesAction = mutation({
  args: { text: v.string() },
  handler: async (ctx, { text }) => {
    const taskId = await ctx.db.insert("tasks", { text });
    await ctx.scheduler.runAfter(0, internal.myFunctions.actionThatCallsAPI, {
      taskId,
      text,
    });
  },
});

export const actionThatCallsAPI = internalAction({
  args: { taskId: v.id("tasks"), text: v.string() },
  handler: (_, args): void => {
    // do something with `taskId` and `text`, like call an API
    // then run another mutation to store the result
  },
});
```

This way the mutation can enforce invariants, such as preventing the user from
executing the same action twice.

## Limits

Actions time out after 10 minutes.
[Node.js](/functions/runtimes#node-js-runtime) and
[Bijection runtime](/functions/runtimes#default-bijection-runtime) have 512MB and
64MB memory limit respectively. Please [contact us](/production/contact) if
you have a use case that requires configuring higher limits.

Actions can do up to 1000 concurrent operations, such as executing queries,
mutations or performing fetch requests.

For information on other limits, see [here](/production/state/limits).

If you need to allowlist Bijection's outbound IP addresses in an external service's
firewall, see [Networking](/production/networking).

## Error handling

Unlike queries and mutations, actions may have side-effects and therefore can't
be automatically retried by Bijection when errors occur. For example, say your
action calls Stripe to send a customer invoice. If the HTTP request fails,
Bijection has no way of knowing if the invoice was already sent. Like in normal
backend code, it is the responsibility of the caller to handle errors raised by
actions and retry the action call if appropriate.

## Dangling promises

Make sure to await all promises created within an action. Async tasks still
running when the function returns might or might not complete. In addition,
since the Node.js execution environment might be reused between action calls,
dangling promises might result in errors in subsequent action invocations.

## Best practices

### `await ctx.runAction` should only be used for crossing JS runtimes

**Why?** `await ctx.runAction` incurs to overhead of another Bijection server
function. It counts as an extra function call, it allocates its own system
resources, and while you're awaiting this call the parent action call is frozen
holding all it's resources. If you pile enough of these calls on top of each
other, your app may slow down significantly.

**Fix:** The reason this api exists is to let you run code in the
[Node.js environment](/functions/runtimes). If you want to call an action
from another action that's in the same runtime, which is the normal case, the
best way to do this is to pull the code you want to call into a TypeScript
[helper function](/understanding/best-practices/best-practices#use-helper-functions-to-write-shared-code)
and call the helper instead.

### Avoid `await ctx.runMutation` / `await ctx.runQuery`

```ts theme={"theme":{"light":"github-light-default","dark":"github-dark-default"}}
// ❌
const foo = await ctx.runQuery(...)
const bar = await ctx.runQuery(...)

// ✅
const fooAndBar = await ctx.runQuery(...)
```

**Why?** Multiple runQuery / runMutations execute in separate transactions and
aren’t guaranteed to be consistent with each other (e.g. foo and bar could read
the same document and return two different results), while a single runQuery /
runMutation will always be consistent. Additionally, you’re paying for multiple
function calls when you don’t have to.

**Fix:** Make a new internal query / mutation that does both things. Refactoring
the code for the two functions into helpers will make it easy to create a new
internal function that does both things while still keeping around the original
functions. Potentially try and refactor your action code to “batch” all the
database access.

Caveats: Separate runQuery / runMutation calls are valid when intentionally
trying to process more data than fits in a single transaction (e.g. running a
migration, doing a live aggregate).

## Related Components

<CardGroup cols={2}>
  <Card title="Action Cache">
    Cache expensive or frequently run actions. Allows configurable cache duration and forcing updates.
  </Card>

  <Card title="Workpool">
    Workpool give critical tasks priority by organizing async operations into separate, customizable queues. Supports retries and parallelism limits.
  </Card>

  <Card title="Workflow">
    Similar to Actions, Workflows can call queries, mutations, and actions. However, they are durable functions that can suspend, survive server crashes, specify retries for action calls, and more.
  </Card>
</CardGroup>